The present invention relates to an electronically controlled fuel supply apparatus for an internal combustion engine, wherein parameters representative of operating conditions of the engine are detected as electric signals which are then fed to an electronic control device to derive optimum quantity of fuel to be supplied to the engine, to thereby effect the fuel supply control on the basis of the derived value produced from the electronic control device.
At present, there is a great demand for a reduction of noxious components contained in the exhaust gas discharged from the internal combustion engine and a decrease in the fuel consumption of the engine.
In an effort to meet the demand, various electronic control devices have been developed for controlling electronically the quantity of fuel supplied to the internal combustion engine.
In general, the electronic fuel control device is implemented in a form of LSI (Large Scale Integrated) circuit. Since the upper limit of temperature at which such control circuit can be used effectively and reliably is relatively low, it is common in practice to install the fuel control device within a chamber of a motor car (e.g. driver's chamber). Consequently, a large number of signal transmission conductors of great length are required for establishing electric connection between the electronic fuel control device, on one hand, and the fuel supply device as well as various sensors which are installed in the vicinity of the internal combustion engine, on the other hand. The sensors of course serve to detect the parameters representing the operating conditions of the engine. It is obvious that the use of the signal conductors of great length is not preferable from many standpoints.
Recently, an attempt has been proposed to reduce the length of the signal conductors by mounting the electronic control device on a main body of the fuel supply apparatus, as is disclosed in U.S. Pat. No. 3,788,287.
However, when the electronic control device is to be mounted on the body of the fuel supply apparatus, the former has to be constructed by using electronic circuit elements or parts which exhibit high heat-resistance properties, involving increased manufacturing cost, because the fuel supply apparatus is thermally coupled to the engine through an intake manifold and is possibly subjected to a high temperature in the range of 80.degree. C. to 100.degree. C. particularly when the engine is operated at a high speed.